Apparatus for accomplishing sonic fusion welding and the like involving variable impedance load factors



April 22, 1969 5 BOD|NE JR 3,439,409

APPARATUS FOR ACCOMPLISHING SONIC FUSION WELDING AND THE LIKE INVOLVINGVARIABLE IMPEDANCE LOAD FACTORS Filed March 24, 1966 Sheet INVENTOR.

58 l m ALBERT 6.

flfro/ZNEY Apnl 22, 1969 A. G. BODINE. JR 3,439,409.

APPARATUS FOR ACCOMPLISHING SONIC FUSION WELDING AND THE LIKE INVOLVINGVARIABLE IMPEDANCE LOAD FACTORS Filed March 24, 1966 Sheet 2 of 5 Apnl22, 1969 A. G. BODINE. JR 3,439,409

APPARATUS FOR ACCOMPLISHING SONIC FUSION WELDING AND THE LIKE INVOLVINGVARIABLE IMPEDANCE LOAD FACTORS Filed March 24, 1966 Sheet of 5 I N VENTOR.

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flrrolz NEV 3,439,409 AND THE FACTORS Sheet 4 of5 A. G. BODINE. JRAPPARATUS FOR ACCOMPLISHING SONIC FUSION WELDING LIKE INVOLVING VARIABLEIMPEDANCE Low i 9 m9 m9 mm:

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A INVENTOR. ALBERT 6. BOD/NE -.T2

A ril 22, 1969 Filed March 24.

flrrazzw/EY April 22, 1969 A. G. BODINE. JR 3,439,409

APPARATUS FDR ACCOMPLISHING SONIC FUSION WELDING AND THE I LIKEINVOLVING VARIABLE IMPEDANCE LOAD FACTORS Filed March 24, 1966 Sheet 5Of 5 ALBEQT 6. Boom/@Je INVENTOR.

14 v-rozm/E V United States Patent Oflice 3,439,409 Patented Apr. 22,1969 APPARATUS FOR ACCOMPLISHING SONIC FU- SION WELDING AND THE LIKEINVOLVING VARIABLE IMPEDANCE LOAD FACTORS Albert G. Bodine, In, LosAngeles, Calif.

(7877 Woodley Ave., Van Nuys, Calif. 91406) Filed Mar. 24, 1966, Ser.No. 537,163 Int. Cl. B23k 27/00 US. Cl. 29-470.3 5 Claims ABSTRACT OFTHE DISCLOSURE Parts to be welded together are supported with thesurfaces to be joined in contact with one another. A resonator member iscoupled to each of the parts and an orbiting mass oscillator isconnected to each of said resonator members. The orbiting massoscillators are driven at frequencies such as to cause resonant elasticvibration of the associated resonator members slightly below the peakresonant frequencies for each. The sonic energy is transmitted to thesurfaces to be joined, generating heat at such surfaces thereby fusingthe parts together.

This invention is directed to a novel process of sonic vibratorywelding, to methods and apparatus for application of such process formaking certain types of weld joint, and to a novel acoustic circuitcapable of carrying out such process effectively.

A welding process called friction welding is now known, wherein twoparts to be welded are rotated together under pressure until the heatgenerated thereby causes a softening of the metal. The rotation is thenstopped and the parts forged together, generally with application ofadditional pressure. The process presents the problem of stopping therotation precisely before the softened metal is disrupted, and theprocess is inapplicable for various reasons in many situations.

Sonic, non-fusion welding, particularly in the ultrasonic range, hasbeen applied to two thin workpieces in contact with one another, forexample, by transmitting lateral vibrations to one of the pieces along acoupling stem from a .magnetostriction transducer, or the equivalent.The laterally vibratory coupling stem engages against an outside surfaceof the workpiece to which it is coupled, and vibrates laterally in theplane of this outside surface. Apparently, through frictional vibrationsof the coupling stem against this outside surface of the workpiece, avibratory shear stress is established in the piece, and with thesimultaneous application of pressure, a sort of crystal interlock withthe other piece can be produced. The ternperature is below the fusiontemperature, and this is therefore not a case of fusion welding, butessentially a coldweld process.

The sonic Welding process of the present invention is of a novelvibratory, friction-fusion type, involving transmission of sonicvibratory energy through or into a workpiece to be welded, in a mannerto cause vibration of the workpiece relative to another workpiece whichis to be Welded to the first and which is being held against the latter.Use of the word sonic should not be understood as implying limitation tothe subjective limits of audibility, but includes frequencies both aboveand below the audible range. It refers instead to vibrations in thenature of sound waves, often characteristically, but not necessarily,within the audible spectrum. The metal of the two workpieces is heatedand softened by the ensuing vibratory friction, and welds by fusion. Asthe material fuses, and the weld then sets up, certain substantialchanges take place in acoustic impedance at the weld, and a principalfeature of the present invention is that these changes in impedance areacoustically accommodated to advantage in the practice of the invention,as will appear hereinafter.

It is a characteristic of the practice of the present invention thatthere be employed a resonant acoustic circuit, including an oscillatoror vibration generator, and a tuned vibration transmitter, or resonator,acoustically coupled and mechanically connected to the vibratedworkpiece. The vibrated workpiece, as well as the mating workpiece towhich the former is to be welded, are part of the resonant acousticcircuit. The tuned vibration transmitter maybe a circuit element inaddition to the vibrated workpiece, or may comprise a partof, or be theentirety of, the vibrated workpiece. In most cases, and in the preferredpractice, the transmitter or resonator part of the circuit ispredominantly of a distributed constant character, with elements of massand elasticity distributed throughout it, so as to vibrate at resonancein a resonant standing wave pattern. The circuit may often containlumped masses or compliances, however, which may substantially modifythe standing wave pattern, or give it a complex character. It is alsopossible to practice the broad invention with a discrete acousticcircuit involving substantially only lumped constants, e.g., a vibrationgenerator, and a resonator and load combination comprised simply oflumped compliance and mass elements.

The present invention is reliant for success upon certain basicprinciples of acoustics of considerable obscurity. An acoustic systemsuch as is utilized in the practice of the invention amounts to adiscrete resonant acoustic circuit, inclusive of a vibration generator,a resonant, elastic, acoustic energy transmitter, or elastic resonator,and a load, which is the work. The generator and transmitter orresonator components constitute an acoustic tool"; the Work constitutesthe varying impedance load which receives sonic energy from the acoustictool; and the whole comprises a discrete acoustic circuit. These circuitelements and their interrelationships, in turn, often involveconsiderations of impedance, frequency, wavelength, resonance, phaseangle, power factor, and the like, and such parameters must be orderedso that the work acts as a working part of this acoustic circuit, andthe result desired follows from energization and operation of thecircuit. The ability of the invention to carry out assigned tasksusefully and effectively depends of course upon the operationaleffectiveness of the circuit, and therefore upon how well the circuithas been contrived to carry out the work process in hand.

The fundamental system of the present invention depends upon use of acertain orbital-mass type of vibration generator in the acousticresonant circuit mentioned above. It has been mentioned earlier that thesite of the weld undergoes certain changes in impedance during theprocess, and these have certain effects such as on resonance vibrationfrequency and power factor. The orbitalmass vibration generator uniquelyaccommodates these changes in the course of the welding process, as willbe stressed hereinafter.

The orbital-mass generator may take any of various mechanical forms, ofwhich the simplest is a mass eccentrically mounted on a shaft turning ina bearing, so that the mass generates a centrifugal force which isreactively opposed by the bearing. The bearing is on a support frame, inresponse to the centrifugal force so generated and applied, exerts aperiodic inertial. force on whatever may support it or be coupledthereto. Some improved forms of orbital-mass generator or oscillator aredisclosed in my Patent Nos. 2,960,314 and 3,217,551. In these patentsare disclosed orbital-mass oscillators comprising a cylindrical massrolling around the inside of a bearing race ring, and a ring-shaped massspinning on a bearing pin. In some cases, the generator may be driven byan electrical motor such as an induction motor, or,

Where increased speed responsiveness to load is desired, by a seriesmotor. In others, as in the case of rollers or rings, the drive may beby an air or other fluid jet directed against the roller or ring. Thus,in many cases, a sliptype drive is used. In all cases, there is anorbiting mass comprised of a weight driven so as to travel around aclosed circular path, which path is determined by a circular bearingforcibly constraining the weight to travel in this curved path. Thebearing then experiences a powerful rotating reaction force caused bythe weight moving along its circular path, which force is periodic innature because each point spaced around the bearing is periodicallysubjected to this force. Together with its support frame, the bearing isthus a reactive coupling output device.

Also, in all cases, the hearing has a support frame, as aforesaid,adapted for making the actual coupling to the system to be vibrated. Themass of the bearing and support frame may be very considerable inrelation to that of the orbiting mass. The momentum imparted to thisconsiderable mass'must be equal to that of the small orbital mass, andsince the velocity of the small orbital mass is quite high, the motionof this considerable mass is thus relatively low. I therefore have theadvantage of a large mass moving periodically with great force ormomentum, but through small displacement distance at relatively olwvelocity. This represents a condition of relatively high impedance(defined hereinafter) in the support frame, i.e. in the generator outputcoupling element, such as is uniquely suited to the circuit requirementsof the present invention.

Such a vibration generator may be arranged and utilized so as to deliverfrom the generator support frame, or coupling means, a continuouslyrotating force vector. In the more usual case, however, the desired oruseful output is an alternating force doing work in reverse directionsalong a given direction line, and such a force, and other very importantadvantages to be mentioned, are obtained by combining with theorbital-mass generator a suitable resonator system, such as a relativelymassive elastic resonator bar. The bar is, for example, attached at oneend to the support frame of the generator, so that it has impressedthereon periodic output impulses from the generator. The bar may then,for example, have such a lenght in relation to the frequency orperiodicity of the generator (circuits per second of the orbital mass)as to vibrate longitudinally in a half-wavelength or fundamentalresonant standing wave pattern. The end of the bar attached to thegenerator support frame, together with the latter, then vibratelongitudinally of the bar; the opposite end of the bar, which may be thework performing end, vibrates longitudinally in opposite phase to thefirst mentioned end; and a mid-region of the bar has minimized vibrationamplitude. The latter region is the location of a node or pseudonode ofthe standing wave, while the moving ends are at antinodes of the wave.The bar will be seen to ulternately elastically elongate and contractand by this motion may do work. This standing wave performance is aresonant phenomenon, and in this case, assuming a uniform bar, andneglecting lumped constant effects of the masses at the two ends of thebar, occurs when f=s/2h, where f is the fundamental resonant frequency,s is equal to the velocity of sound in the bar, and h is the length ofthe bar. At resonance, the mass and compliance reactances of thevibratory system are equal and cancel one another, the impedance tovibration of the masses of the system is thereby reduced to that owingto friction (actual work done), and vibration amplitude in the bar isresonantly magnified by a large factor. In effect, the blockingimpedance of the masses along the direction line of the bar has beenvery greatly reduced, generator output force consumed by this impedancealong this direction line is correspondingly diminished, and largevibratory motion along the direction line of the bar is attained.

In this resonant performance, the large necessary vibratory masses ofthe system are tuned out and consume none of the output force from theorbital-mass generator. They are moved by elastic restoration forcesexerted by the deformed compliances, which are in turn elasticallydeformed, of course, in decelerating the masses. Thus the massiveelastic system vibrates with no consumption of force save for that lostin friction and in doing useful work.

A further considerable advantage in the system is that the masses willthen vibrate at substantial amplitude (exhibit large vibrationaldisplacement), and become a powerful acoustic flywheel, storingconsiderable energy. The masses become an advantage. The system exhibitsresonant magnification of motion. This gives a system which can build upto high vibratory power level; and the energy storage flywheel effectalso gives the ability to ride over irregularities presented by the workload.

From the foregoing it will be appreciated that an orbiting mass, such asone confined to traveling around a circular path, delivers its reactionagainst this confinement as a reactive centrifugal force whichinherently rotates so as to be a force oriented successively in alldirections in a plane. On the other hand, as has been shown, theresonating bar, or equivalent, can, for example, be a longitudinallyelastically vibratory bar. Such resonant motion is thus typicallyvibration back and forth along a line or path. Since such resonance,however, eliminates the blocking effect of the masses only along thisline or path, the vibratory amplitude will be of substantial magnitudeonly along this same line or path, even though the oscillator isdelivering force in an infinite number of directions radiating aroundthe focal center of the mass orbit. The above described natural blockingeffect of the masses thus prevents the vibration from being substantial,except in the path direction or directions along which the phenomenon ofresonance has eliminated the blocking mass effect as described. Theperformance of the orbitalmass oscillator, in combination with theresonance exerted thereby, and which I term orbit-resonance, can thuspolarize the resulting vibration from the orbiting mass, and givesstability of vibratory motion along this line of orientation. Thevibration stroke can thus be confined along a predetermined path.

Another very important property of the present system is a uniquefrequency stability. An orbiting mass vibration generator by itself cantend to change its frequency from time to time. However, in theorbit-resonance system, this orbiting mass is acoustically coupled to aresonant vibratory system, with dimensional proportions adjusted so thatthe orbiting mass is very conscious, so to speak, of the impedance ofthe resonant system. Within the resonant frequency range, and especiallyin the preferred operating region on the low side of the resonance peak,where resonant magnification exhibits sharply increasing amplitude inresponse to increasing frequency, the orbitingmass oscillatorautomatically tends to lock in and hold to a stable frequency condition.The explanation is as follows: A slight increase in frequency, resultingfrom any cause, produces an increase in vibration velocity andamplitude. This results from the reactive part of the impedance havingbeen thereby diminished. The phase angle of the orbital mass is thusimproved, so more work can be done ifmore drive effort is supplied.Thus, more drive torque is required of the orbiting-mass oscillator,and, in turn, more drive effort from its drive source or prime mover.Thus, the vibratory system, operating near resonance, feeds back ademand for additional drive effort. Using a drive source whose driveeffort on the oscillator remains constant, or whose output isinsufiicient to develop the increased drive torque demanded at theincreased frequency, or using as a source a prime mover which isinversely speed-responsive to load (e.g., an induction motor, or forgreater responsiveness, a series motor), the system responds by actuallyreducing the drive speed of the oscillator in the face of this increasein demand for drive torque. Thus the initially assumed slight increasein frequency is corrected. The system similarly responds to a slightdecrease in frequency by moving further from resonance, and through aprocess which will now be evident, produces increased speed at theorbitingmass vibration generator such as to correct the assumed slightdecrease in frequency. The system thus automatically holds a determinedfrequency. Bearing in mind the impedance equation F: VZ, where F isdrive force exerted by the oscillator on the vibratory system, and V isthe velocity of vibration, an increase in frequency toward the resonancepeak must be accompanied by increase in V and in the total energy of thesystem, and the force factor F must be sufiicient that this will be donenotwithstanding a decrease in the reactive component of the impedance Zas resonance is approached. The force F must be increased to reach orsustain the new conditions, and thus the above mentioned demand forincreased torque takes place. This increase in torque is not supplied.Therefore, the frequency reduces following, or in response to, theincrease which first took place. The system thus has inherent frequencystability.

The combined system of an orbital-mass vibration generator and resonatorhas a unique performance which is exhibited in the form of a greatereffectiveness and particularly greater persistence in sustained sonicaction as the work process goes through successive phases involvingchanges of working conditions. The orbiting mass generator in thiscombination is able to sustain its development of power for the load asthe sonic energy absorbing environment changes with the variations insonic energy absorption by the load. It does this by automaticallychanging its phase angle, and therefore its power factor, with thesechanges in the resistive impedance of the load.

This can be explained as follows: Consider the orbitalmass oscillatorused in this invention, say of the type involving a roller masstraveling in a circular path around the inside of a cylindrical bearing,and assume this bearing to be fixed to a free end of an elastic bar, theaxis of the bearing being perpendicular to the length axis of the bar.Assume further that the roller mass is driven around the bearing at afrequency of s/2h cycles per second, where s is the velocity of sound inthe bar and h is the length of the bar, so that the bar is driven by thecyclic output force exerted by the bearing to undergo halfwavelengthstanding wave vibration. The bar then alternately elastically elongatesand contracts, at the cyclic frequency of the roller mass. Thelongitudinal velocity of the driven end of the bar, and also the forceexerted by the bearing on the bar, can then be plotted as sinusoidalwaves. With no net work done on or through the bar, the force wave thenlags the velocity wave by 90. The phase angle of the roller in its raceis such that at this time it moves longitudinally of the bar in stepwith the oscillator end of the bar. This is a condition of 90 phaseangle, a power factor of zero, and zero net work done. Assume now thatthe vibrating bar is subjected to substantial friction. The velocitywave loses amplitude, and the roller mass automatically undergoes anangular shift in position within its race so as to bring the sinusoidalforce wave more into phase with the velocity wave. The phase angle isthus reduced, and power factor increased the necessary amount for thegenerator to develop and supply the energy consumption required by thefriction now encountered. correspondingly, if the friction were large tostart, and subsequently diminished, the phase angle would be small tostart, and would subsequently go towards or to substantially 90 withprogressive elimination of friction.

Also, if the load on the orbital-mass oscillator-resonator combinationshould vary in mass reactance, or elastic compliance reactance, duringoperation, the frequency and phase angle of the oscillator will shift toaccommodate these changes. A change in reactance of a vibratory systemcan be accomplished, for example, if during vibratory operation, a parthaving mass is welded to a vibrating part. Such a change in reactanceresults in a change in impedance, phase angle, and resonance frequency.If the prime mover is one which has slip, or is speedresponsive totorque, there is a resulting automatic feedback of torque to the primemover which drives the orbiting-mass oscillator such as to re-establishstable op eration at a new resonant frequency, and with adjusted phaseangle and power factor which. automatically accommodate the addedreactance and any remaining energy consuming load. Any changes inmagnitude of either or both the friction or energy consuming part of theload and the reactive part of the load are thus automaticallyaccommodated by the invention so that the oscillator sustains itsdevelopment and transmission of power into the load throughout all suchchanges.

To accomplish these performances the resonant system must besufficiently large relative to the resistive impedance so as to exhibitresonant magnification. Moreover, the orbital-mass generator must havesufficient output force and impedance so as to accomplish such resonantmagnification, even with the resistive load; and this generator outputmust also be large enough to cause the stabilizing torque load on thegenerator drive. However, the generator output and input should not beso high as to cause a power flow which overrides the resonant feedbackphenomenon above described. This resonance phenomenon could beundesirably buried if it is simply caught between a very powerfulgenerator and a large resistive load.

The invention is further disclosed hereinafter in a number of practicalapplications, all of which involve the broad principles of theinvention, but each of which involves specific unique features ofinvention. These will be disclosed and stressed in connection with thedescriptions of illustrative apparatus for carrying out the severalpractical applications referred to just above.

Before proceeding with the detailed descriptions of these severalspecies of the invention, however, there will be presented a discussionof certain principles of sonics necessary to an understanding of theinvention, some of which are generally familiar to those skilled in theart, but a number of which are not.

SONIC DISCUSSION Certain acoustic phenomena disclosed in the foregoingand hereinafter, are, generally speaking, outside the experience ofthose skilled in the acoustics art. To aid in a full undertsanding ofthese phenomena by those skilled in the acoustics art, and by others,the folowing general discussion, including definition of terms, isdeemed to be of importance.

By the expression sonic vibration I mean elastic vibrations, i.e. cyclicelastic deformations, such as longitudinal, lateral, gyratory,torsional, etc., produced in an elastic structure, or which travelthrough a medium with a characteristic velocity of propagation, andwhich are often at resonance in the structure, or are involved withtravelling or standing waves. If these vibrations travel longitudinally,or create a longitudinal wave pattern in a medium or structurt havinguniformly distributed constants of elasticity and mass, this is thesimplest form of sound wave transmission. Regardless of the vibratoryfrequency of such sound wave transmission, the same mathematicalformulae apply, and the science is called sonics irrespective of audiblelimits. In addition to purely distributed constant systems, there can beelastically vibratory (sonic) systems wherein the essential feature ofmass appears wholly or in part, as a localized influence or parameter,known as a lumped constant; and another such lumped constant can be alocalized or concentrated elastically deformable element, affording alocal effect referred to variously as elasticity, modulus, modulus ofelasticity, stiffness, stiffness modulus, or compliance, which is thereciprocal of the stiffness modulus. Fortunately, these constants, whenfunctioning in an elastically vibratory system such as mine, havecooperating and mutual influencing effects like equivalent factors inalternating-current electrical systems. In fact, in both distributed andlumped constant systems, mass is mathematically equivalent to inductance(a coil); elastic compliance is mathematically equivalent to capacitance(a condensor); and friction or other pure energy dissipation ismathematically equivalent to resistance (a resistor).

Because of these equivalents, my elastic vibratory systems with theirmass and stiffness and energy consumption, and their sonic energytransmission properties, once they have been conceived of as acousticcircuits, can be viewed as equivalent electrical circuits, where thefunctions can be expressed, considered, changed and quantitativelyanalyzed by using well proven electrical formulae.

It is important to recognize that the transmission of sonic energy intothe interface or work area between two parts to be moved against oneanother requires the above mentioned elastic vibration phenomena inorder to accomplish the benefits of my invention. There have been otherproposals involving exclusively simple bodily vibration of some part.However, these latter do not result in the benefits of my sonic orelastically vibratory action.

Since sonic or elastic vibration results in the mass and elasticcompliance elements of the system taking on these special propertiesakin to the parameters of inductance and capacitance inalternating-current phenomena, wholly new performances can be made totake place in the mechanical arts. The concept of acoustic impedancebecomes of paramount importance in understanding performances. Hereimpedance is the ratio of cyclic force or pressure acting in the mediato resulting cyclic velocity or motion, just like the ratio of voltageto current. In this sonic adaptation impedance is also equal to mediadensity times the speed of propagation of the elastic vibration.

Impedance is important to the accomplishment of desired ends, such aswhere there is an interface. A sonic vibration transmitted across aninterface between two media or two structures can experience somereflection, depending upon differences of impedance. This can be availedof, if desired, to cause large relative motion at the interface.

Impedance is also important to consider if optimized energization of asystem is desired. If the impedances are adjusted to be matchedsomewhat, energy transmission is made very effective.

Sonic energy at fairly high frequency can have energy effects onmolecular or crystalline systems. Also, these fairly high frequenciescan result in very high periodic acceleration values, typically of theorder of hundreds or thousands of times the acceleration of gravity.This is because mathematically acceleration varies with the square offrequency. Accordingly, by taking advantage of this square function, Ican accomplish very high forces with my sonic systems.

An additional important feature of these sonic circuits is the fact thatthey can be made very active, so as to handle substantial power, byproviding a high Q factor. Here this factor Q is the ratio of energystored to energy dissipated per cycle. In other words, with a high Qfactor, the sonic system can store a high level of sonic energy, towhich a constant input and output of energy is respectively added andsubtracted. Circuit-wise, this Q factor is numerically the ratio ofinductive reactance to resistance. Moreover, a high Q system isdynamically active, giving considerable cyclic motion where such motionis needed.

Certain definitions should now be given:

Impedance, in an elastically vibratory system, is, mathematically, thecomplex quotient of applied alternating force and linear velocity. It isanalogous to electrical im- 8 pedance. The concise mathematicalexpression for this impedance is where M is vibratory mass, C is elasticcompliance (the reciprocal of stiffness, or of modulus of elasticity)and f is the vibration frequency.

Resistance is the real part R of the impedance, and represents energydissipation, as by friction.

Reactance is the imaginary part of the impedance, and is the differenceof mass reactance and compliance reactance.

Mass reactance is the positive imaginary part of the impedance, given by211'fM. It is analogous to electrical inductive reactance, just as massis analogous to inductance.

Elastic compliance reactance is the negative imaginary part ofimpedance, given by 1/21rfC. Elastic compliance reactance is analogousto electrical capacitative reactance, just as compliance is analogous tocapacitance.

Resonance in the vibratory circuit is obtained at the operatingfrequency at which the reactance (the algebraic sum of mass andcompliance reactances) becomes zero. Vibration amplitude is limitedunder this condition to resistance alone, and is maximized. The inertiaof the mass elements necessary to be vibrated does not under thiscondition consume any of the driving force.

A valuable feature of my sonic circuit is the provision of enough extraelastic compliance reactance so that the mass or inertia of variousnecessary bodies in the system does not cause the system to depart sofar from resonance that a large proportion of the driving force isconsumed and Wasted in vibrating this mass. For example,

a mechanical oscillator or vibration generator of the type normally usedin my inventions always has a body, or carrying structure, forcontaining the cyclic force generating means. This supporting structure,even when minimal, still has mass, or inertia. This inertia could be aforce-wasting detriment, acting as a blocking impedance using up part ofthe periodic force output just to accelerate and decelerate thissupporting structure. However, by use of elastically vibratory structurein the system, the effect of this mass, or the mass reactance resultingtherefrom, is counteracted at the frequency for resonance; and when aresonant acoustic circuit is thus used, with adequate capacitance(elastic compliance reactance), these blocking impedances are tuned outof existence, at resonance, and the periodic force generating means canthus deliver its full impulse to the work, which is the resistivecomponent of the impedance.

Sometimes it is especially beneficial to couple the sonic oscillator orvibration generator at a low-impedance (high-velocity vibration) region,for optimum power input, and then have high impedance (high-forcevibration) at the work point. The sonic circuit is then functioningadditionally as a transformer, or acoustic lever, to optimize theeffectiveness of both the oscillator region and the work deliveringregion.

For very high-impedance systems having high Q at high frequency, Isometimes prefer that the resonant elastic system be a bar of solidmaterial such as steel. For lower frequency or lower impedance,especially where large amplitude vibration is desired, I use a fluidresonator. One highly desirable specie of my invention employs, as thesource of sonic power, a sonic resonant system comprising an elasticresonator member in combination with an orbiting mass oscillator orvibration generator, as above mentioned. This combination has manyunique and desirable features. For example, this orbiting massoscillator has the ability to adjust its input power and phase to theresonant system so as to accommodate changes in the work load, includingchanges in either or both the reactive impedance and the resistiveimpedance. This is a very desirable feature in that the oscillator hangson to the load even as the load changes.

It is important to note that this unique advantage of the orbiting massvibration generator accrues from the use thereof in the acousticresonant circuit, so as to comprise, with the work or load, a completeacoustic system or circuit. In other words, the orbiting mass vibrationgenerator is matched up to the resonant part of its system, and thecombined system is matched up to the acoustic load, or the job to beaccomplished. One manifestation of this proper matching is acharacteristic whereby the orbiting mass oscillator tends to lock in tothe resonant frequency of the resonant part of the system.

As will be noted, this invention involves the application of sonic powerwhich brings forth some special problems unique to this invention, whichproblems are primarily a matter of delivering effective sonic energy tothe particular work process involved in this invention. The workprocess, as explained elsewhere herein, presents a special combinationof resistive and reactive impedances. These circuit values must beproperly met in order that the invention be practiced effectively.

The invention will be further understood from the following detaileddescription of a generic representation and a. number of specificillustrative embodiments thereof, reference for this purpose being badto the accompanying drawings, in which:

FIG. 1 is a diagrammatic view of an acoustic circuit which, with itsevident equivalents, is generically illustrative of the broad invention;

FIG. 2 is an exploded view of a plurality of engine head castingcomponents, as seen in a vertical transverse section, which are to befusion welded in accordance with the invention;

FIG. 3 is a plan view of the engine head components of FIG. 2, inassembly with one another, and having connected thereto certain devicesby which elastic vibration energy is transmitted into the castingcomponents;

FIG. 4 is a transverse section taken on line 4-4 of FIG. 3;

FIG. 5 is a section taken on line 5-5 of FIG. 4;

FIG. 6 is a section taken on line 6-6 of FIG. 4;

FIG. 7 is a transverse section taken on line 7-7 of FIG. 5;

FIG. 8 is a view similar to FIG. 3, but to a smaller scale, showing amodification;

FIG. 9 is a side elevational view with some parts shown in verticalmedial section, of a sonic machine for fusion welding of the abuttingends of two sections of pipe;

FIG. 10 is a transverse section taken as indicated by line 1010 of FIG.9;

FIG. 11 is a view similar to FIG. 9, but showing the parts in adifferent position;

FIG. 12 is a section taken on line 1212 of FIG. 9;

FIG. 13 is a section taken on line 1313 of FIG. 9;

FIG. 14 is a diagrammatic view showing the pipes being welded in theapparatus of FIGS. 9-13 and showing certain standing wave diagramsdemonstrating the operation of the machine;

FIG. 15 is a diagrammatic view illustrative of the phasing of a pair ofvibration generators as used in the system of FIGS. 9-14;

FIG. 16 is a side elevational view, with parts broken away in medialsection, showing an illustrative application of the invention to thewelding of a pair of universal joints to opposite ends of a tubularshaft;

FIG. 17 is a transverse section taken on line 17-17 of FIG. 16;

FIG. 18 is a detail section taken on line 18-18 of FIG. 16;

FIG. 19 is a diagrammatic view of the apparatus of FIG. 16, showing alsoa standing wave as set up in the hollow shaft in the operation of thesystem;

FIG. 20 is a side elevational view, with parts in vertical medialsection, showing an application of the invention to the fusion weldingof a pin or shaft to a surface area on a large body; and

FIG. 21 is a detail section taken on line 21-21 of FIG. 20.

Reference is first directed to FIG. 1, illustrative schematically of thebasic acoustic system of the invention, and of all the subsequentlydescribed species thereof. An oscillator or elastic vibration generator,of the orbital-mass type, as described hereinbefore, is designated at O,and is slip-driven by a driver or prime mover P. A tuned elasticvibration transmitter or elastic resonator T is coupled to thisgenerator and to the work or load, designated generally at L. In thepreferred case, here diagrammed, the member T is coupled between thegenerator and the load, though broadly it is only necessary that theseelements all be acoustically intercoupled and the generator andresonator thus could be attached to the load at a common coupling point.The load L is to be understood to have an impedance which variesmaterially during the performance of the work, i.e., with consumption ofsonic energy, thereby modifying in an advantageous manner theperformance of the generator 0. It consists in this instance of twoelements to be welded, w and w, which are in frictional, vibrational,sliding contact, as represented, and one of which is on or positivelyattached to, or forms a part of, the vibration transmitter T, so as tobe directly vibrated by the vibrations transmitted "to it and into it bythe latter. Thus, in one typical and common case, for example, thevibrations are transmitted elastically along the transmitter, and thenceinto and along or within the workpiece connected to the transmitter. Theentire system, composed of generator 0, vibration transmitter orresonator T, and load L, constitutes a discrete resonant acousticcircuit. Thus, the generator 0 is driven by the prime mover P at afrequency at which the circuit is in the range of resonance. To obtainimportant frequency stabilization benefits, the prime mover drives thegenerator at a frequency in the resonance range, but somewhat under thefrequency for peak resonance. Further, the prime mover for the generatoris matched in the acoustic circuit in such a manner that it will justsupply the drive torque necessary to establish and maintain operation ina resonant range but below the peak of resonance. As mentionedhereinabove, a slip-drive type of prime mover is capable of doing this,e.g., a fluid motor, with just enough torque to hold operation up to theresonance range, but insufiicient to obtain the peak of resonance. Also,an electric motor inversely speed-responsive to load, such as aninduction motor, or a series-wound motor, can carry out this function.The components 0, T and L of this discrete circuit all enterintrinsically into the resonance performance, and present a combinationof mass and elastic compliance reactances which cancel out internally ofthe acoustic circuit at its resonant operating frequency.

The vibration transmitter T may vibrate longitudinally, laterally,torsionally, or gyrationally (which is a special case of two lateralvibrations in quadrature). The oscillator is understood to be connectedproperly to the transmitter to produce any desired one of such modes ofvibration. The vibration transmitter is positively connected to, orforms an integral part of, one of the workpieces, so that workpiecevibrates directly and in full accord with the portion of the transmitterto which it is connected.

The load L has a frictional resistance factor R, owing to the workpiecesw and w vibrating against and relatively to one another, and in theoperation of the system, this factor R may hold constant for a time, andthen as temperature rises by reason of the friction, and the metal ofthe parts softens, the frictional factor diminishes, and may finallydrop substantially to zero. In the meantime the parts w and w fuse andbecome forged or welded to one another, so that the reactance of thepart w is added to the system. Thus the impedance of the load changes,by

diminishing friction R, often accompanied by increasing reactance. Thediminishing friction, and also the increasing reactance, lead to areduced power factor, a higher Q, and a modified resonance frequency (insome forms lowered, by addition predominantly of mass reactance). Tothese changes, the slip-driven orbiting mass oscillator instantlyresponds, continuing to deliver power at resonance, preferably justunder the peak of resonance, and following any changes in resonancefrequency, always with the proper phase angle to sustain the loadthroughout the changing conditions of the process.

Following fusion of the parts, vibration is of course terminated, andthe parts are cooled, or allowed to cool.

In the work process represented in FIG. 1, the vibration transmitter Tis typically a longitudinally elastically vibratory bar, vibrating atresonance, in an effectively halfwavelength standing wave pattern(actually, some what shorter owing to lumped constant effects at the endof the bar). As the weld is made, the mass of the added workpiece isadded onto the end of the bar and vibrates therewith. Typically, thisadds inductance or mass reactance, while frictional resistance isgreatly reduced, and the resonant frequency of the system accordinglylowers. The slip-driven orbital-mass generator follows this loweringresonance frequency, and changes its phase angle and power factor, asmentioned hereinabove. In this process, the changes referred to arefacilitated by an acoustic lever effect, by which the impedance of theload is matched or adjusted to the impedance of the generator by theintervening vibration transmitter bar. Thus, the ratio of cyclic forceto vibration amplitude at the generator is matched to a higher ratio ofcyclic force to vibration amplitude at the location of the weld,particularly after the weld has set up somewhat, and if the part weldedon is of large mass. In such case the amplitude of vibration in theelastic vibration bar is of course greater at the generator than at theweld. In any case in which this effect is not needed, the elasticvibration transmitter bar need not intervene between the generator andthe weld. Instead, by a mere reversal of parts, the generator may bedirectly connected to one of the workpieces to be welded, and theelastic bar then simply coupled to the generator. In such case, theelastic bar still plays an essential role, since it is a necessaryelement to the acoustic resonant circuit, and acts to afford the tuningto resonance and automatic resonant frequency accommodation essential tothe invention.

In this case, as mentioned, the progress of the work is accompanied by adecrease in resonant frequency, which is followed by the orbital-massgenerator. There are also cases in which changing character of the loadduring the work process results in an increase in resonant frequency,and as pointed out hereinafter, such a change will also be followed bythe orbital-mass vibration generator.

Reference is next directed to FIGS. 2-7, inclusive, showing anillustrative application of the invention to the practical problem ofsonic welding together of the components of a die-cast structure, inthis case a cylinder head, cast initially in the form of simplecomponents which are then welded into an integral structure by theprocess of the invention. A great many practical advantages accrue byway of increased production and reduced cost of production in carryingout this process. First, a complicated structure can be made bydie-casting, using the sonic welding techniques of the invention,without requiring complicated cores and inserts in the die-castingprocess. Thus a structure having hollow passages and cavities, like acylinder head or engine block, could be made economically by adie-casting process if the requirements for the usual cores and insertswere to be eliminated. Great economy is achieved in using thedie-casting process, if the parts can be put through the die-castmachine at a rapid rate, with simple structures having only surfaces andgeometry of general shape which allow easy direct separations of themold parts. That is to say, a die-cast part is very economical if it canbe made up of a form such that the various views of the part presentonly hollowedout cavities opening to the outside. Then, if the finalstructure is to have hollow passages going through it, various componentdie-cast parts having such cavities opening to the outside can be weldedtogether to make the final structure. The need in the past has been fora good process of fastening or bonding the various die-cast componentstogether, so as to form the :firial structure with its hollow passagesand various cavities, such as exist in engine cylinder heads and blocks.For instance, the water jacket passages and the gas flow passagesrepresent a considerable problem in trying to die-cast an engine blockor engine cylinder head in one step. On the other hand, if thesepassages are made simply by putting hollowedout parts together along acommon parting plane or planes, a fairly complicated final structurewith interior openings or passages can be easily made.

In FIGURES 2-7, a cylinder head is composed of four components 21, 22,23 and 24, made to fit together on three parallel joining planes such as25, 26, and 27. The drawings show a somewhat conventional moderncylinder head, with certain water jackets, gas passages, valve pockets,etc., and it will be clear from the drawings how the joining planes havebeen selected so that the several components 2124 can be die-cast assimple parts which, when assembled, form therebetween the severalpassageways, cavities, pockets, etc.

As shown in FIG. 4, the four components 21-24, inclusive, stillunwelded, are assembled against one another in proper alignment, and areheld together under pressure by elastic stems such as engaging the outersides of the outermost components 21 and 24, and projectingperpendicularly towards these components 21 and 24 from base plates 32.The latter are backed up by clamping plates 34, to which are linked thecylinders of hydraulic or pneumatic jack means I, only fragmentarilyshown. As viewed in FIG. 4, relative vibratory motion is to be createdin certain of the components of the structure in the direction of thedouble-headed arrows a, and it will be seen that any vibratory motion soimparted to the upper and lower components 21 and 24 will beaccommodated by lateral vibration of the pressure-exerting stems 30. Thepressure applied by the hydraulic cylinders 35 need not be exceptionallyhigh, as it is only necessary to bring the several joining planesurfaces into contact.

For the purpose of accomplishing relative vibration of the componentparts in directions parallel to the planes 25, 26 and 27, I here show arepresentative system in accordance with the invention involving a pairof orbital-mass vibration generators or oscillators and 41 connected bytuned elastic vibration transmitter bars 42 and 43 to the twointermediate casting components 22 and 23, respectively. The bars 42 and43 may also be termed elastic resonators. As appears in FIG. 4, the barsextend substantially parallel to the planes 25, 26, 27, and theoscillators 40 and 41 are arranged to produce longitudinally vibratorymovements in the bars. As here illustratively shown, the connection fromthe end portions of the bars 42 and 43 to the casting components 22 and23 is made by means of adapters 45 screwthreaded at one end into theends of the bars, and at the other end into screwthreaded sockets 48formed in component walls 49 and 50, respectively. Pins 52 connect theadapters 45 to the end portions of the bars 42 and 43.

The generators 40 and 41 on the ends of the elastic bars 42 and 43,respectively, may be any of the types discussed in the introductory partof the specification, for example, though any other found suitable maybe substituted in certain of the broader aspects of the invention.However, the generators are by preference, for reasons stressedhereinabove, i.e. to accomplish certain of the most importantperformances and benefits of the invention, of the orbital-mass type. Ashere shown, the oscillators are of the type involving an inertia massring spinning on a pin or axle under the drive of a jet of air. Thus,with reference to FIGS. 4 and 5, there is formed on the end of the bar42 a somewhat enlarged cylindric head 55 with a side wall 56 at one endthereof. A hollow pin 57 is mounted concentrically inside housing 55 onside wall 56, and is thus fixed and acoustically coupled to the elasticbar 42. Coupled to the hollow pin 57 of each oscillator is a pressureair or other fiuid conduit 58, leading from a suitable source undercontrolled pressure, preferably equipped with a pressure control meanssuch as control valve, not shown. The hollow pin 57 is provided insidethe confines of the cylindric head 55 with tangentially oriented airdischarge ports 59. Positioned on the pin 57 is an orbital-mass orinertia ring '60 in the form of a cylinder with an inside diametersomewhat greater than the outside diameter of the pin 57, and also ofsuch outside diameter as will just clear the inside surface of thecylindric housing member or head 55 when the ring is in engagement withthe pin 57. Jets of air issuing from the tangential ports 59 aredirected tangentially against the inner periphery of the ring 60, andthus the ring 60 is caused to spin or whirl on the pin 57, so as toexert on the latter, by reason of the centrifugal force which isdeveloped, an inertial force which rotates about the longitudinal axisof the pin 57. As here simply shown, the ring 60 is confined axiallybetween the inside wall 56 of the oscillator head 55 and an annularflange 61 formed on the pin 57 just outside the ring 60. Air from ports59, spent after doing work on the ring 60, is discharged as indicated bythe arrows.

The rotating inertial force, or force vector, exerted by the spinninginertia ring 60 on the pin 57 of each gen erator is eventually appliedto the generator head 55, and thence to the end of the correspondingelastic bar 42 or 43, as the case may be. An alternating component offorce is thus exerted longitudinally along each of said bars, as well asa lateral component; but by adjusting the frequency of this force toresonance of the system for the longitudinal direction of the bars,longitudinal resonant standing waves are set up in the bars. Thus, thepressure of the air driving the generators is made such as to assure aresonant vibration frequency in the circuit, and preferably a frequencywhich is in the resonance range, but on the low side of that for peakresonance in the acoustic circuits, as mentioned earlier, and referredto again presently.

In the present case, the two elastic vibration transmitter bars 42 and43, together with the castings 22 and 23 connected thereto, are drivenin a half-wavelength, fundamental-frequency, longitudinal resonantstanding wave pattern, modified in each case by the lumped constanteffect of the relatively substantial casting mass. Assuming theidealized case of a relatively uniform bar, with no very material lumpedmass at the ends, the resonant frequency becomes f=s/2h, as givenhereinabove. At this resonance frequency, the bars alternatelyelastically elongate and contract with substantial amplitude under thecyclic driving force received from the oscillators 40 and 41, thevibration amplitude becoming magnified as reactive blocking impedancecancels out at the resonant frequency. In this performance, velocityantlnodes (regions of maximized vibration amplitude) occur at the twoextremities of each bar, and velocity nodes or pseudonodes (regions ofminimized vibration amplitude) occur at approximately the mid-points ofthe bars if the castings are relatively light. The ends of the bars, andparts connected thereto, vibrate in opposition to one another, withamplitudes inversely proportional to the magnitude of any lumped massesat these ends.

With the relatively massive castings on the ends of the bars, thehalf-wavelength standing Wave vibration patterns are materiallymodified, the nodal points shifting along the bars to points near thecasting parts, and the vibration amplitude of the casting part becomingthereby somewhat reduced, notwithstanding resonant magnification.

Also, the added, largely lump-form mass of the large casting partssomewhat reduces the resonance frequency. This reduction in vibrationamplitude, however, is often of no disadvantage in the practice of theinvention. However, when it is desired to counteract this effect,several steps are available. First, the vibration transmission bars 42and 43 can be made relatively heavy, and also provided in several pairssuitably connected to the casting parts. In FIG. 3, for example, twosuch pairs of bars are connected to the casting parts, and it will beunderstood that these bars may be massive enough, or enough pairs of thebars and generators used, to avoid shifting of the nodal pointsundesirably close to the casting parts. The system of FIGS. 27, usingtwo such pairs of bars, is of advantage in that, since the oscillatorsare not synchronized, the casting parts will not only be vibratedlongitudinally of the bars, but will also be somewhat rocked in anangularly oscillating manner Whenever the oscillators do not happen tobe synchronized] with one another.

It might also be noted at this time that the oscillators are, as anoption, somewhat offset from the longitudinal centerlines of the bars 42and 43. Lateral vibrations (nonresonant) are thereby set up in the bars,and these vibrations can contribute helpfully to the vibratory processinvolved in theweld.

Finally, the bars 42 and 43 will be seen to be optionally of somewhatdifferent lengths, so that the resonant frequencies for the two areunequal. Further assurance is thereby provided of good relativevibration between the casting parts 22 and 23 directly vibrated thereby.

As a further variant, I may use one pair of two very massive bars 42aand 43a, with corresponding large oscillators 40a and 41a as representedin plan in largely diagrammatic FIG. 8, the bars being forked at theends and suitably fixed to the casting parts, as represented. It will beunderstood that in FIG. 8, there will be one bar over the other, in thisrespect much in the arrangement of FIG. 4. The system here is similar toa pair of the oscillators 40 and 41 and bars 42 and 43 as describedhereinabove, but simply wider and more massive, so as to approach moreclosely the mass of the work.

In any event, the casting parts will by such means be vibrated againstone another, under light pressure, causing them to heat, soften at theirboundaries, and then fuse to one another. As the parts gradually softenand then fuse to one another, some very subtle changes and performancestake place. First, friction is progressively re duced, and second, asthe casting parts 21 and 24 fuse to the parts 22 and 23, respectively,additional mass loading is added to the system. The operation in thisconnection is as already described in connection with FIG. 1, and neednot be re-described.

According to one mode of practicing the invention, the oscillators 40and 41 are operated simultaneously, though not synchronously, causingall four casting parts to weld together in one process. Thus the twoinside casting parts 22 and 23 vibrate against and relatively to oneanother. The outside parts will tend to remain relatively stationary byvirtue of their inertia, so that the casting parts 22 and 21 alsovibrate on and relatively to one another, as do the casting parts 23 and24. Alternatively the oscillator 40 can be operated first, so as tovibrate and weld the part 22 to the parts 21 and 23. The oscillator 41is then operated, with or without simultaneous operation of oscillator40, to weld the part 24 to the already integrated parts 21-23.

The oscillators will be seen to be r'esistively loaded by the frictionalresistances of the casting parts rubbing against one another, as well asreactively loaded by the mass and compliance factors of the casing partsas well as the remainder of the vibratory system. At resonance, the massand compliance factors of the loading cancel out, and vibrationamplitude is magnified, as explained earlier. To achieve resonance, theair driving the oscillators is regulated in pressure and Volume to drivethe oscillator mass-rings at a frequency which is just below thefrequency for peak resonance. The driving fluid then drives theoscillator rings with substantial slip, as will be clear. Under theseconditions, a frequency stability is achieved, in that the resonant barback-reacts on the oscillator mass ring to hold it at the predeterminedfrequency, just below the peak of resonance, as explained earlier. Thusif the vibration frequency tends to increase, the ring must speed up,and in so doing, deliver more output force to carry the process uptowards the resonance peak. But by a feedback effect from the resonatingbar by which the oscillator is thereby more heavily loaded, and anunsatisfied demand made for additional torque, such tendency isimmediately overcome, and the ring is thus constrained against risingabove its original frequency. The frequency of the system thus tends tolock in and hold to a predetermined operating frequency on the low sideof peak resonance frequency. The corrective performance upon tendencyfor decrease in frequency will be understood from the foregoing. Thesystem thus tends to hold a constant frequency, at least for constantload.

However, when the casting parts 2 1 and 24 are added onto the vibratingsystem, the mass loading increases. This reduces the frequency forresonance, and the orbitalmass vibration generators, driven asdescribed, follow this reduction in frequency, as explained above.

Reference is next directed to FIGS. 91S, inclusive, illustrative of anapplication of the invention to the welding of pipe joints, applicablewith particular efficiency and advantage to aluminum pipe. In thispractice of the invention, the mode of sonic vibration may be atorsional mode, a gyrating mode, or a lateral mode. The illustrativemachine disclosed herein shows particularly a torsional mode. In thecarrying out of the invention, a novel machine has been contrived whichis characterized by both compactness and easy portability, and thus isadapted for use out in the field where pipe lines are being laid.

A principal advantage of the sonic pipe welding process of the inventionis that it can accomplish fusion welding without causing residuallock-up stresses in the joint such as occurs with normal electric are orother conventional welding processes. Also, with the sonic process, itis possible to readily obtain a leak-proof joint, with a very closeapproach to one hundred percent of the strength of the original pipe.The process is applicable with alloys which are diflicult to weld byelectric or acetylene type welding. Moreover, the use of sonic fusionwelding eliminates fire hazards acompanying electric or acetylenewelding of long pipe joints.

The sonic fusion pipe welding machine of the invention is designated byreference numeral 70, and is shown applied to the welding together ofthe ends of two pipes 71 and 72, of which the latter may be the end pipesection of a previously laid pipe line, and the former may be a new pipelength to be added.

The machine is shown to include a hanger yoke 74, suspended by a cable75 from any suitable means of support not shown. The hanger yoke 74 hastwo yoke arms in the form of spaced sleeves or collars 76 which receivea horizontal suspension pipe 77 projecting in opposite directionstherefrom, and the pipe 77 is secured to the hanger 74 as by welding.

On one side of hanger 74, the pipe 77 has welded thereto a dependingsuspension means 80 for a clamp means 81 for clamping tightly to thepipe 72. On the opposite side of hanger 74, a somewhat similarsuspension means 82 is provided, but is arranged for sliding movementalong the pipe 77, and this suspension means 82 carries a clamp means 83for the pipe 71, the clamp means 81 and 83 being similar to one another.

Rotatably mounted on the pipe 77 between collars 76 is a housingassembly 86 for an electric motor 87, to the shaft of which is coupled amilling cutter 88 adapted for engagement with the ends of both of pipes71 and 72 when the pipe 7 1 has its extremity substantially in theposition indicated in dot-dash lines 71a in FIG. 9. The housing assembly86 has fixed thereto a spur gear 90' surrounding and rotatable on thepipe 77, and meshing with this spur gear is a spur gear 91 on a shaft 92journaled in the lower end portion of a bracket arm 93 projecting fromhanger 74. On spur gear shaft 92 is fastened an operating lever 95. Whenthe milling cutter 88 has completed its operation of finishing otf theends of pipes 71 and 72 (the pipe 71 being in position 71a, FIG. 9), thelever 95 may be swung to rotate the housing assembly 86, through gears81 and 90, so as to swing the milling cutter 88 to a position ofclearance relative to the pipes 71 and 72 (FIG. 10). The two pipe clampmeans 81 and 83 are similar, and will next be described. The lowerportion of the suspension means 80 or 82, as the case may be, comprisesa thick and massive plate member 100, affording the acoustic circuit amass element M (FIG. 14). Plate has a transverse tapered bore 101receiving, with clearance, the corresponding pipe member, as shown. Apair of arcuate wedge slips 102 are receivable in the tapered bore 101on opposite sides of the pipe, and when forced inwardly axially of thepipe, are wedged radially inward to clamp the pipe tightly therebetween.The wedge slips 102 are so forced inwardly by hydraulic pressure exertedagainst pistons 104 connected to the slips by links 105 and working incylinders 106 mounted in the plate 100', all as clearly shown in FIG. 9.Hydraulic fluid is introduced into the cylinders 106 underneath thepistons to effect clamping action by fluid introduced under pressure viapassageways 1107, and may be exhausted from the spaces above the pistonsvia passageways 108.

As will be evident, the hanger plate members 100, which may thus be verytightly clamped to the pipes 71 and 72, are relatively massive, andthus, from the acoustic standpoint, mass-load the pipes at the clampingpoints. An inductive or inertial mass reactance is thus added to thepipe at a predetermined distance from the free extremity thereof, andthereby, as will be described in more particular hereinafter, a nodalpoint for the sonic standing wave set up in the pipe is established atthe clamping point.

A pipe alignment jig, generally designated at 110, is suspended by alink 111 from the arms 76 of the yoke 74 on the side of the fixedsuspension means 80, as illustrated, and this jig provides alignmentguide bushings surrounding the pipes 71 and 72 closely adjacent theopposed extremities of the latter, and affords mountings for componentsas presently to be described. The bushings 112 preferably comprisesuitable plastic rings 113, composed of a suitable material such as afiber-filled molded phenolic resin. The plastic rings 113 may be moldedinside cylindric casings 114. The latter are tightly received inside thehub portions 116 of jig frames 117, in which are tightly mounted,outside of and on opposite sides of the alignment bushings 112, a pairof electric drive motors 118, which may be induction motors, orpreferably, in many cases, series-wound D-C motors having a substantialinverse speed-responsive characteristic to load. The motors 118 havedrive shafts which are parallel with the pipes 71 and 72 and which driveorbitalmass type vibration generators or oscillators 120 of the generalcharacter heretofore described. These generators 120 may be, forexample, of the type shown in FIG. 1 of my Patent No. 3,217,551, towhich reference may be had for a thorough understanding. Sufiice it tosay that the generators 120, when driven by the motors 118, producerotating force vectors turning about the axes of the motor shafts, andexerted by the housing of the generator on the structure that issupporting this housing. In this case, the housing of each vibrationgenerator 120 is tightly received in the outer portion of a transverseframe 123, which has a central boss portion 124 formed with a taperedbore 125 which surrounds, with clearance, the

pipe 71 or 72, as the case may be, and which is clamped tightly to thepipe by wedge slips 126 inserted inside the tapered bore 125 and forcedtightly against the pipe by tightly setting up holding screws threadedthrough the Wedge slips and into the hubs 124. The frame affords, ineffect, two radially oppositely extending torque arms 127 clamped to thepipe. Thus, the rotating force vector generated by each oscillator 120is exerted on the free end of the corresponding torque arm, and isapplied by said arm as an oscillatory torque on the portion of the pipe71 or 72 clamped by that torque arm.

It is to be noted that each of pipes 71 and 72 thus has clamped thereto,near its free end, through a pair of torque arms, a pair of orbital-massvibration generators. These are phased to coact torsionally in anadditive sense, as will be described more fully hereinafter. As oneoptional means for phasing the two pairs of vibration generators onopposite sides of the joint between the two pipes, I here show the motorshafts 130 and 131 to be provided with a slip coupling 132, which may beof any suitable typefor example, a splined shaft in a splined couplingsleeve, as here represented. The reason for this phasing will bereferred to more particularly in the ensuing discussion of operation.

To complete the description of the jig 110, the two jig frames 117 aresuitably interconnected with one another, as here shown. By being formedat the bottom with sleeves 136, one of which tightly receives aconnecting shaft 137, and the other of which slidably receives saidshaft. The frames 117 may thus move toward one another when the pipeends are moved together. The shaft 137 is shown to project from theouter extremities of the sleeve members 136, and to pass with clearancethrough apertures 138 formed at the bottom of the oscillator supportframes 123. In the operation of the device, the frames 123 oscillatetorsionally through a small angle, and the apertures 138 accommodatesuch torsional deflection. At the same time, the projection of the shaft137 through the apertures 138 in the oscillator frame 123 assures orfacilitates rough alignment of the parts.

Operation is as follows: The machine is assembled first with the pipe72, being positioned and clamped thereon as illustrated in FIG. 9. Thenew pipe length 71 to be added is then brought up, run through the clampmeans 83, vibration generator frame 123, the alignment bushing 112, andon up to a position such as illustrated at 71a in FIG. 9. It is thenclamped both by clamp means 83, and the torque arm wedge slips 126. Atthis time, the opposed end portions of the two pipes 71 and 72 willnormally be somewhat in the path of the motor driven milling cutter 88as the latter is swung in a plane transversely of the pipes by operationof lever 95. Thus the ends of the pipe are provided with nicely squaredend surfaces which, because of the alignment of the pipes assured by theguide bushings mounted on the jig, will come into good aligned abutmentand full-face engagement with one another when milling cutter 88 hassubsequently been swung aside and the pipe 71 advanced toward the right.It Will of course be understood that the drive motor 87 drives themilling cutter 88, and that the swinging action of the milling cutterwhile rotation takes place is accomplished by swinging of theaforementioned lever 95. When the pipe end finishing operation has beencompleted, the milling cutter is swung out of the way by means of handle95, as to the position of FIG. 10, and the pipe 71 then moved to theright to engage the pipe 72, as shown in FIG. 9. This movement may beaccomplished by the hydraulic jack indicated generally at 139, pivotallyconnected at one end to the suspension means 82, as indicated at 140,and linked at the other end to an ear 141 formed on the adjacent arm ofthe yoke 74. The internal details of the hydraulic jack 139 need not beshown, since hydraulic jacks are well known. However, as will beunderstood, admission of pressure fiuid to the chamber of this jack willbe understood to actuate a plunger therein so as to slide the suspensionmeans toward the right on the pipe member 77 until the pipe 71 abuts thepipe 72. This hydraulic jack 139 can also be used to maintain a lightpressural contact of the two pipe ends against one another.

The torsional vibratory action inducted in the pipes 71 and 72, and themanner of producing this vibratory action by the vibration generatorsdescribed hereinabove, will now be explained. Consider first theleft-hand pipe member 71. This pipe member is tightly clamped at acertain distance back from its free end by the relatively massiveclamping means 83. This point of the pipe, therefore, is substantiallyrigidly held, both by virtue of the clamping action, and by virtue alsoof the inertia or mass M of the relatively heavy clamping means appliedthereto. Accordingly, the oscillatory torque exerted on the pipe 71,applied to the pipe near the milled-off, free extremity thereof, causesthis portion of the pipe to elastically twist in first one direction andthen the other, with the amount of the twist progressively decreasingfrom the point of application of the oscillator torque to the pointrigidly held by the clamp means 83 and made steady by the mass M. Byproperly relating the length of the pipe between the clamp means 83 andthe free end of the pipe to the frequency of torsional oscillation, aquarter-wavelength, resonant standing wave pattern of a torsional modecan be set up in that portion of the pipe, their being a node N of thisstanding wave at the clamp means and mass M, and an antinode V of thestanding wave at the free extremity of the pipe. Those skilled in theacoustics art are familiar with this relationship. Similar Y torsionalresonant standing wave vibration or oscillation is set up in the pipe72, and reference is made to FIG. 14 for a diagrammatic representationof these actions. At Si is represented a quarter-wavelength torsionalstanding wave for the pipe 71 from the node to the antinode, andsimilarly at Si is represented the corresponding standing Wave for thepipe 72. It is further a preferred feature of the invention that whenthe pipe 71 is twisting in one direction, the pipe 72 in twisting in theopposite direction, the purpose being to have maximized relative motionbetween the ends of the pipe, so that these will work frictionally onone another to a maximized extent and thus readily accomplish a fusionweld. It is of course not strictly necessary that the two pipes 71 and72 oscillate precisely 180 out of phase, though this is preferred as itaffords a maximum frictional action. However, the process can be carriedout just so that there is some frictional rubbing of one pipe end on theother as the two pipes undergo their torsional socillation. Referringfurther to FIG. 14, it will of course be understood that the standingwave diagrams Si and Si represent the amplitude of torsional elasticdeflection in each of the pipes 71 and 72 between the nodes N and theantinodes V at different points along the pipe, the amplitudes, asshown, being maximized at the free extremities of the pipes.

Synchronization and phasing of the various generators is preferablyobtained in the following manner. Reference is directed to diagrammaticFIG. 15, showing the pipe 71, the two torsion arms 127 and the twovibration generators mounted on the two torsion arms. Each vibrationgenerator involves an inertia mass rotor rolling around a raceway 151 inan orbital path, so as to apply to the raceway 151 and thus to theexternal housing of the vibration generator a rotating force vectorturning about the central axis Y of the raceway. It will now be observedthat if the orbital rotors 150 are phased in opposition to one another,as represented to be in FIG. 14, the components of radially directedforce in line with the torque arms 127 will always be equal and opposedand therefore cancel within the structure of the torque arms 127 and theintervening pipe 71. Also, the components of force at right angles tothe arms 127 will always be equal and opposed, and thus will all cancel.

However, these latter forces exert force couples, i.e. torsionaldeflecting forces, on the pipe, and it will be seen that these are firstin one direction and then the other as the rotors go around the twoopposite sides of the raceways. In summary, I thus apply to an endportion of each of the two pipes 71 and 72 an alternating force couple,such as elastically twists the two end portions of the two pipesalternately in reverse directions.

The aforementioned synchronization or phasing of the two orbital-massrotors 150 of each pair of oscillation generators on the same side ofthe pipe joint may be accomplished in various ways, such as by gearingtogether the two vibration generators, or by phasing properly the twodriving motors 118. Even without any such phasing, however, the twoorbital-mass rotors are found to selfsynchronize themselves entirelyautomatically when acting as component parts of a resonant vibratorysystem. This subject was described in my aforementioned Patent No.3,217,551. The synchronization or phasing of the two orbital-mass rotors150 of each pair of generators 120 is thus simply accomplished in any ofvarious ways.

As pointed out hereinabove, it is also preferable that the pairs ofgenerators 120 clamped to the two pipes 71 and '72 on opposite sides ofthe pipe joint operate in phase opposition, so as to assure oppositedirections of oscillatory twisting of the two pipe ends on one another.To this end, and for simple illustration, the shafts of the two lowermotors 118 have been coupled together by a coupling 132, and if thebacks of the motors on the opposite sides of the pipe joint to be madeshould of course have opposite normal directions of rotation. Of course,if the four motors all face in the same direction, they can all have thesame normal direction of rotation. Assuming such an arrangement to havebeen made, the vibration generators directly driven by the two lowermotors can then be preliminarily phased in 180 opposition, and each ofthese lower motors can then be arranged for provisions for phasingproperly with the motor above it, or will automatically phase with themotor above it, in the manner heretofore described.

However these phasing arrangements are carried out, the result is thatthe two ends of the two pipes 71 and 72 oscillate torsionally in lightcontact with one another. To accomplish proper performance in accordancewith the invention, each pipe end is at the velocity antinode of atorsional elastic resonant oscillation of a quarterwavelength of thepipe, and this is accomplished by providing a proper length of pipe fromthe clamp means and mass M to the free extremity of the pipe such that aresonant, quarter-wavelength standing wave performance, in a torsionalmode, takes place in that length of pipe at the frequency established bythe drive motors 118. Under these circumstances, a large amplitude oftorsional vibration takes place at the two extremities of the two pipes,and thus the two pipes are frictionally rubbed on one another atsubstantial amplitude under a resonant performance. Of course, as inearlier described forms of the invention and in the introductory portionof this specification, it is to be understood that the motors 118 areactually given a normal performance characteristic such as to drivenormally at a speed or frequency which drives the vibration generatorsjust under the frequency for the peak of resonance; and, as alsodescribed hereinabove, the drives are preferably of a slip type and withsuch characteristics as to be inversely speed-responsive to load. Thesystem then operates with frequency stability, and with capability foraccommodating to changes in the impedance of the load, which in thiscase is the pair of pipe extremities vibrating torsionally against oneanother.

At the outset, the load will be seen to have a large energy dissipativefactor or resistance. As the fusion welding process goes forward, thisresistance is modified, and reactances are introduced, with consequentchange in the impedance of the load. Reference is again directed 20 toFIG. 14, showing at the top the two standing wave performances of thetwo pipes 71 and 72 prior to softening of the metal by the heat offriction and thus prior to the beginning of fusion. As the two pipe endsheat up, they begin to soften and to fuse to one another.

Initially, frictional resistance between the pipe ends oscillatingagainst one another is high, meaning, of course, a high power factor forthe orbital-mass vibration generators. This resistance factor may or maynot increase as temperature first increases; but when the metal softensand begins to fuse, the frictional factor decreases, and each shaftexperiences the effect of reactance from the other to which it is thenpartially joined, so that there is a change in impedance. The phaseangle thus begins to increase and the power factor to decrease. Themotordriven orbital-mass vibration generator adjusts to these changes inload, as explained heretofore, thus maintaining good impedanceadjustment to the load. As the shaft ends progressively undergo fusionto one another, the wave pattern shifts from those of Si and Si throughthat represented at I, where the vibration amplitude is. decreased,producing at the joint a sort of pseudonode Ni where the antinodes wereonce located, to the final pattern at P, where there may besubstantially or nearly a node N at the joint. There is then an antinodeat V and it will be seen that the wavelength of the pattern has thenapproached half of what it was initially, while the frequency of thewave approaches double its initial frequency. In other words, there isnow a resonant frequency at double that at the beginning of operation;and the motor-driven vibration generators automatically follow thisincrease in resonance frequency. They do this because, as resonancefrequency increases incrementally, there is a momentary increment ofdecreased load on the drive motors at the original frequency. The drivemotors respond instantly with increased speed. Also, the motors areagain made insufliciently powerful to drive the system up to and overthe peak of resonance, and the system tends to stabilize just below peakresonance, as before. The system again therefore accommodates forchanges in impedance, and accommodates also for changes in resonancefrequency as the parts are joined.

Reference is next directed to FIGS. 1618, showing an additionalapplication of the invention wherein a lateral mode of vibration isutilized to form a fusion weld between the ends of a tubular shaft and apair of universal joints.

A tubular shaft is designated generally by the reference numeral 160,and to the two ends of this shaft are to be fusion welded two universaljoints 161. As here shown, the butt end or root of each of theseuniversal joints includes a tubular member 162 receivable with a freefit inside the end portion of the shaft 160, and formed with a shoulder163 adapted to abut the end of the shaft 160. The weld is to be made onthe facing and abutting surfaces on the end of the pipe and the shoulder163.

The universal joint 161 is completed by two arms 164 supporting auniversal joint pin 165, and in the apparatus here shown, the universaljoint at one end is supported by an arcuate seat 166 engaging the pin165 and projecting from a suitable fixed support generally representedby the numeral 168. At the other end, the pin 165 is engaged by a seat166 which is on a plunger shaft 169 projecting from a hydraulic jack 170on a suitable fixed support 172. It will be understood that the plungershaft 169 has inside cylinder 170 a plunger head working in acylindrical chamher, and that suitable hydraulic lines are provided,together with suitable controls, whereby the plunger 169 may be extendedor retracted to engage and support a universal joint assembly such asdescribed, or release it when the work has been finished.

The present application of the invention involves the use of a lateralmode of resonant elastic vibratory action in the hollow shaft 160, witha wave pattern such as represented in the diagram of FIG. 19. Toaccomplish the wave pattern as represented, I mount on the central region of the shaft 160 an orbital-mass vibration generator of the typeheretofore described, and as indicated in the drawings by the referencecharacter 175. The generator 175 delivers to its exterior housing 176 arotating force vector, turning about an axis X-X'. The housing 176 willbe seen from FIG. 17 to have an arcuate seat 177 which engages the lowerside of the shaft 160, while the upper side of said shaft, just aboveseat 177, is engaged by an arcuate seat 178 on a pad or head 179 on thelower end of a plunger 180 extending from a hydraulic jack 181. Thehydraulic jack 181 and the body plate 182 in which the aforementionedseat 177 is formed, are connected by tie rods 183, and thus extension ofplunger 180 and clamping head 179 under hydraulic control of pressurefluid delivered to the hydraulic jack 181 affords a tight clampingengagement of the generator 175 to the center portion of the shaft 160.

In the simple form here shown, the generator housing 176 has,concentrically located with the transverse axis X-X', a bore 184containing a raceway cylinder 185, the latter having formed therein arecessed, cylindrically formed raceway surface 186 for an inertia roller187. The latter is driven to run around the raceway surface 186 by meansof air under pressure supplied via an air hose 188 and leading to a jetor nozzle passageway in the body 176 and the raceway member 185 to opentangentially inside the raceway surface 186. Air under pressuredelivered from this tangential nozzle drives the rotor 187 to spin aboutthe raceway surface 186. This will be seen to be a slip-drive type ofvibration generator as referred to hereinabove. The cylindrical rotor187 rolling around the inside of the raceway surface 186 generatesWithin the raceway member 185, and thus within the housing 176 holdingthe latter, a radial force vector turning about the axis X-X', aspreviously mentioned.

It is to be understood that the pressure and volume of air delivered viathe hose 188 must be such as to drive the generator rotor 185 at afrequency approximating, but preferably on the low side of, the resonantfrequency for a mode of lateral standing wave vibration, preferably thefull-Wavelength mode as diagrammed at $1 in FIG. 19. Under theseconditions, as represented in this diagram, there is a velocity antinodeV, or region of maximized vibration amplitude, at each end of the shaft,as well as a velocity antinode V at the center, while there are nodes N,or regions of minimized vibration amplitude, at points approximately 20%of the length of the shaft from each end, as represented. The vibrationin the shaft 160 will be seen to take place, because of resonance in thelateral node, in planes transversely of the shaft, but it will beevident that the vibration generator 175 will also deliver to the pipe160 a component of alternating force disposed longitudinally of thepipe. By driving the generator at the frequency for resonance in thelateral mode, or preferably, as heretofore explained, just below thefrequency for lateral resonance at peak amplitude, the normal blockingimpedance for vibration in the transverse mode is greatly reduced, sothat large amplitudes of vibration may be experienced at the antinodesin transverse planes (in this case, vertically). On the other hand, thecomponents of vibratory force exerted by the generator 175 in directionslongitudinal of the shaft 160 are not near to any longitudinal resonantfrequency of the shaft, and therefore longitudinal components ofvibration in the shaft 160 are of small magnitude and can be neglected.

Thus, in the operation of the system, the two opposite end portions ofthe shaft 160- are vibrated in transverse planes, i.e. in the plane ofthe two end surfaces of the shaft, at a resonant frequency of the shaftfor the transverse resonant standing wave mode employed. The two ends ofthe pipe thus vibrate transversely against the universal joint shoulders163. It will :be evident, of course, that the vibratory amplitudes ofthe end portions of the shaft are relatively small. They are, however,very powerful. The universal joint, on the other hand, is not tightlyenough joined to the shaft 160, prior to welding, that it will be causedby frictional forces to follow the vibratory action of the shaft.Accordingly, the type of sonic vibratory action, at a resonant frequencyof the system, causes relative vibration of the parts, and thereforefrictional heating, until the metal melts and fuses. In thisperformance, changes of impedance take place, analogous to thosedescribed in earlier embodiments of the invention, and in theintroductory portion of the specification, and the orbital-massvibration generator automatically accommodates for these changes, all asheretofore described.

Reference is next directed to FIGS. 20 and 21, showing a finalapplication of the invention, in this case to the fusion welding of ashaft or pin to a surface of a body, in this case using a gyratoryand/or torsional type of resonant elastic standing wave vibration in theshaft.

The shaft, which must be of an elastic material, such as steel, or aresin, is designated generally at 190, and as here shown, has anenlarged head 191 on one end thereof. This head 191 is shown to abutagainst a surface of a body 192, positioned by an abutment 193 securedto the work table, as illustrated. The other end of the shaft isreceived, with clearance, in a socket 194 formed in cup 195, and engagedby a coil compression spring 196 in the bottom of said cup. The cup is'slidable in a bore 197 in a support 197, and is connected via a link198 with the short arm 199 of a clamp lever 200 pivotally mounted at 201on a mounting bracket 202. The lever arm 199 and the link 198 form atoggle, enabling the parts to be positioned by handle 200 so that theleft-hand extremity of the shaft 190 is under spring pressure from thespring 196 during operation, whereby the head 191 on the opposite end ofthe shaft 190 is lightly pressed against the body 192 to which it is tobe welded.

In this application of the invention, a gyratory (or torsionaI) type ofresonant standing wave is set up in the pipe 190, and for this purpose,a vibration generator 205 is clamped to a center region of the shaft190. The generator 205 may be the same as the generator 175 of theembodiment of FIGS. 16-19, but with the exception that the axis of therace ring for the orbital-mass rotor, here designated at 206, and itscylindrical raceway 207, have been turned through 90, so that the axesthereof are parallel with the shaft 190. The orbital-mass rotor 206 actsto generate and apply to the generator housing, and thence to the shaftto which the generator housing is clamped, a rotating force vector,which rotates about a longitudinal axis near and parallel to the shaft.The elastic shaft is thereby set into a bodily gryratory type of motion,which actually amounts to two rectilinear vibrations on axes at rightangles to one another and occurring with 90 phase differencetherebetween. This motion is propagated along the length of the shaft,reflected from the ends thereof, and when the generator frequency iscorrect for resonance, a gyratory type of one-wavelength resonantstanding wave vibration takes place in the shaft. This type ofperformance was fully described in my aforementioned prior Patent No.2,960,314, FIGS. 1-4, and the portion of the specification pertainingthereto. In this type of gyratory action, the end surface of the shaft190, or in this case, of the enlarged head thereon, gyrates bodily atthe resonance frequency in contact with the surface of the body 192, andthus friction is set up sutficiently to heat and melt the metal in theregion of the two engaging surfaces, such that these surfaces fuse toone another.

As in the applications of the invention discussed hereinabove, theorbital-mass vibration generator slip-driven by pressurized fluid, againpresents the advantages of frequency stabilization, accommondation tochanges of impedance, in either or both of the resistive and reactivecomponents thereof, during changing conditions of the 23 work process,automatic adjustment always to required phase angle and power factor, aswell as to any changes in the frequency of resonance, all as discussedhereinbefore.

It will be understood that the acoustic circuit of the invention,diagrammed in FIG. 1, is present in all of the disclosed illustrativeapplications of the invention. It should also be evident that thisacoustic circuit has a breadth of application going beyond that offusion welding, and extending to any process wherein impedance andfrequency changes may be encountered during a work process and wheremaximum performance demands automatic accommodation to these changingfactors.

It is to be understood that the drawings and description are not to beconsidered as limitative on the invention but only illustrative thereof,and that the invention is to be considered as limited only by a fairconstruction of the appended claims.

I-claim:

1. The process of friction fusion welding of two elastic parts to oneanother, that comprises:

supporting said two parts with two surfaces thereof in contact with oneanother;

acoustically coupling to each of said parts an orbitalmass vibrationgenerator and an elastically vibratory resonator comprising a bar memberfor generating and transmitting to the associated part sonic vibrationenergy, with a component of vibration in the plane of said contactingsurfaces; and

driving each of said orbital mass vibration generators at an operatingfrequency in the region of that for peak resonance in the discretevibratory circuit comprised of the generator, the associated resonator,and the associated part whereby to effect vibration of said partsrelative to and against one another in the plane of the contactingsurfaces thereof until said surfaces heat by friction and fuse to oneanother.

2. The subject matter of claim 1, including the feature of operatingsaid orbital-mass generators with slip-drive at a frequency near to butbelow that for peak resonance.

3. The subject matter of claim 1, wherein said parts are two engine headcasting components having plane surfaces in mutual contact; andincluding the procedure of transmitting vibratory sonic energy from saidorbital-mass vibration generators through said resonators functioning aselastic sound wave transmission means to said components, the vibratorysonic energy being transmitted along the longitudinal axes of said barmembers.

4. The subject matter of claim 1, wherein said parts are two elongatedelastic members, such as pipes or the like, to be butt-welded to oneanother, and including the steps of:

holding said elongated members in end-to-end engagement; and

applying said sonic vibration energy to set up resonant standing wavevibration in at least an end portion of one of said members, withvibration in planes transversely thereof, and with a velocity antinodeat the extremity of said one member, and a velocity node at a distanceof one-quarter wavelength along said member from said extremity thereof.

5. The subject matter of claim 1 wherein said vibratory circuits havedifferent peak resonant frequencies, said generators each being operatedin the region of peak resonance for its associated circuit.

References Cited UNITED STATES PATENTS 3,184,841 5/1965 Jones et al.2281 3,234,645 2/1966 Hollander et al. 29--470.3 3,333,323 8/1967Wyczalek l 29-470 WILLIAM I. BROOKS, Primary Examiner.

U.S. Cl.X.R.

